Search PubMed⌕ Search

Biomedical subjects

R D Bock

Publications and source records attributed to R D Bock.

12 recordsLinked to original sources
PubMed1996

High-dimensional multivariate probit analysis.

A computationally practical form of probit analysis for multiple response variables based on an assumed common factor model for the latent tolerances is proposed. Numerical integration over the factor space provides maximum likelihood estimation of the probit regression parameters and of the probabilities of response combinations under the model. The procedure is applied to five variables from the Pneumoconiosis Field Trial, two variables of which were previously analyzed by Ashford and Sowden (1970, Biometrics 26, 535-546).

Algorithms↗
PubMed1985

Tonic, phasic and cortical arousal in Gilles de la Tourette's syndrome.

This study explored the hypothesis that Gilles de la Tourette's syndrome involves a disturbance in arousal modulation. The experimental group consisted of 20 unmedicated subjects with the Gilles de la Tourette's syndrome, and the control group of 20 subjects with chronic medical illnesses (haemophilia, von Willebrandt's disease and diabetes). There were differences between groups in the manner in which log conductance level changed over time during sound and light habituation experiments involving mild levels of stimulation with the Gilles de la Tourette group showing less change in arousal level over trials than the control group. No group differences were found in measures of phasic arousal, rate of spontaneous fluctuations and performance on two tasks that have been related to cortical arousal. It is suggested that the slower change in log conductance level in the Gilles de la Tourette group during the sound and light habituation experiments indicates that reticular activity is more persistent in these patients.

Acoustic Stimulation↗
PubMed1979

A lod score method for detecting linkage on the X chromosone between a marker locus and a major gene locus for a quantitative.

A sequential lod-score method is proposed for detecting linkage on the X chromosome between a marker locus and the locus of a major gene influencing a quantitative trait, The method uses information from sons of doubly heterozygous mothers. The average number of families required to detect linkage is substantially less than that of the fixed sample-size method proposed by Hill.

Female↗
PubMedDate not supplied

Age changes in adult stature: trend estimation from mixed longitudinal data.

Although it is widely accepted that persons become shorter as they grow older, most estimates of the rate of decline are based largely on cross-sectional studies and are confounded by secular changes and individual variation. The present study uses a mixed series of longitudinal physical measurements, obtained by the Busselton Population Studies Group, for nearly the entire adult population of Busselton, Western Australia. All persons in the sample who had a minimum of three measures at 3-year intervals are included in our analysis, regardless of health. Random regressions analysis of the individual height and age data is used to estimate the expected rate of decline of stature with age. A significant sex difference was found, with females declining at a greater rate than males, particularly after the age of 40.

Adolescent↗
PubMedDate not supplied

Comparison of height acceleration curves in the Fels, Zurich, and Berkeley growth data.

A new type of smoothing spline designed for nonparametric estimation of growth acceleration curves was applied to longitudinal measures of height from the Fels, Zurich, and Berkeley growth studies. Landmark features of the individual acceleration curves were located and examined for site effects and site by sex interaction. The curves in each group were structurally averaged by transforming the age scale of each child to align the landmarks with overall means. The modal shapes of the structural average curves were found to be highly similar in the three studies, although the relative number of children who conformed to the modal pattern differed among the studies. Significant site by sex interactions were found in the timing of the landmarks associated with the pubertal growth spurt and with the prepubertal 'midspurt'.

Adolescent↗